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Steel belt drive solves conveyor belt problem

Edited by the Engineeringtalk editorial team Mar 14, 2001

Belt Technologies provide novel solution to conveyor problems used for manufacturing medical diagnostic strips.

When automation systems manufacturer Horizon Instruments was designing a machine for manufacturing medical diagnostic strips, the company faced a challenge due to a requirement of the machine to carry the material through two ovens as part of the manufacturing process.

Belt Technologies was able to solve the problem for Horizon by supplying a precision indexing steel belt drive system able to cope with the temperature changes and cleanliness requirements of the application.

Specialising in designing and developing mainly one-off machines and systems for the diagnostics and pharmaceuticals industries throughout Europe, Horizon Instruments based in Heathfield, Sussex, produces machines for applications such as diagnostic test production, vial filling and capping, laminating materials, cutting and placing, and QC monitoring and testing.

The medical test strips are manufactured from a Mylar backed nitrocellulose material that is cut into strips after reagents have been deposited on to its surface and dried in two ovens.

The material is presented to the system in the form of bands.

During the manufacturing process, each band has one reagent deposited on its surface before passing through the first curing oven.

Next, a further two reagents are applied, prior to being passed through a second oven to be dried again.

Because the test strips are used for medical purposes, the precision indexing conveyor system needs to have a clean, non-contaminating surface on which to place the bands, as well as possessing a low thermal mass that will not cause temperature fluctuations when passing through the ovens.

Belt Technologies provided the solution in the form of a steel belt drive.

The conveyor system consists of two steel belts, each 25mm wide, that support the ends of the bands being produced.

17-7 Condition C stainless steel was used for the belt composition.

This material performs very well when low thermal expansion is required - a necessary consideration to retain indexing pitch accuracy whilst passing through the two ovens.

The complete conveyor is 2.5 metres from centre line to centre line of the pulleys, with stainless steel wires supporting the bands between the belts.

To ensure positional accuracy of the bands, location pins are attached to each belt, whilst slots incorporated in the belts enable sensors to guarantee belt positioning.

Belt Technologies manufactures steel belts and pulleys for diverse applications in many industries.

Available in a range of materials for specific applications, belts offer unique advantages over other drive systems, including high strength to weight ratio, no lubrication requirements and smooth operation.

The non-stretchable belts are also durable and clean room compatible.

Horizon Instruments looked into several drive systems.

However, because of the unique requirements of this particular project, Belt Technologies provided the only feasible solution, as explained by Senior Projects Engineer at Horizon, Angus Woodhams: "We were looking for something corrosion resistant and clean that would not contaminate the bands being produced.

We also needed something with a low thermal mass that wouldn't take heat out of the ovens." "The only other options we had were polymer belt systems but we weren't sure they would handle the oven temperature, or a chain drive which would have been dirty, required lubrication and would have produced particulates.

Chains also have a large thermal mass which could have led to fluctuations in oven temperatures.

When we contacted Belt Technologies they were able to supply all the technical information we needed and provided a very good service." After the success gained with the first machine, Horizon was asked to supply a second similar machine to enable the customer to double production output of diagnostic strips.

And the future? "Now we realise the benefits of steel belt drives we know it is a very useful technology to have in our repertoire and something we would easily be able to use again," concluded Woodhams.

As well as a second and third machine similar to the first Horizon have supplied two other related pieces of equipment which both use Belt Technologies steel belts for conveying in a similar environment.